... whether it be no bulkhead resting at all, socked feet OK ... or TV screen height.
I'm not using social faux pas's as a basis for the line, a bit more pragmatic instead. It's potential for damage . Shoes can easily scuff or dirty bulkheads, hence should be removed if going to place feet on them. Feet on TV screens can potentially damage TV screens = not appropriate, really a no brainer, do people put their feet all over their laptop or tablet screens? (Not to mention get feet all over where people will touch the controls ... although arguably less likely to contaminate than unwashed hands.
As for bare feet vs socks discussion, I'll reserve my views on that but there is a generational element in play here too - we'll leave it at the fact that I'm quite surprised at the number of people wandering around with nice pants/jeans, nice shoes and no socks on .
I just think in the list of grievances on airplanes about antisocial behaviour, feet on bulkheads rates way down the list, when you have people hogging armrests, continuously jabbing IFE screens on the back of seat , leaving their seatbelts unbuckled during turbulence (could fall on other passengers), reclining too quickly, reclining while the person behind is trying to eat their meal, people putting in jamming devices to prevent recline, talking on phones during safety demonstration, being generally rude to flight attendants, getting drunk and violent, taking other peoples seats and refusing to move, leaving children to run riot in Y when sleeping in J, etc etc, consuming all the Krug in F
p I wish, one day maybe).